While my iPhone and iPad are at 15.6.1, my AppleTV 4K is still at tvOS 15.6, no update available. I checked my YouTube app and there was an update. I’m not sure I like it now, HDR videos have a 2 second dropout when switching HDR modes on my LG OLED. And since YouTube inserts commercials, it blanks out 2 seconds of the commercial, so I guess I should appreciate that, but it’s more annoying than anything since it blanks out 2 seconds of the video I was watching.